Genomic testing offers significant promise for improving the diagnosis and treatment of a broad array of medical conditions, but as with all clinical care, preventable errors may occur in its application. A recent study, for example, found that up to a third of clinical genetic tests performed in diagnostic laboratories were incorrectly ordered. Genomic tests may also be misinterpreted or incorrectly communicated. These errors can result in significant harms, including misdiagnosis, poorly directed or ineffective treatment, or false reassurance. As genomic testing is expanded to diverse clinical settings, the potential for errors will increase. Therefore an important opportunity exists, while the infrastructure to enable genomic medicine is still in development, to identify the sources of potential medical error associated with genomic testing and the strategies needed to mitigate them. In other clinical domains, important progress in patient safety has been made by understanding the system failures that underlie most medical errors rather than simply blaming individual providers. Genomic testing is likely to pose novel patient safety challenges due to a rapidly evolving evidence base, the increased involvement of non-specialists in test ordering and interpretation, concerns surrounding genomic privacy, and the implications of genetic findings for biological relatives. To address these challenges we need a better understanding of the range of potential errors associated with genomic testing, from pre-analytic choices to post-analytic counseling, as experienced or anticipated by genetics professionals, patient safety experts, and front-line clinicians. The aim of this study is therefore to identify where medical errors can occur in the delivery of genomic medicine and to evaluate potential systems-based approaches to mitigating error, utilizing the lens of the patient safety. Specifically, the propose investigation will: (1) identify, via key informant interviews, the major categories of medical errors (both preventable and not preventable) expected to arise in the routine delivery of genomic medicine; (2) explore, using focus groups, potential approaches to reducing the incidence of preventable errors in genomic testing, in groups of health providers with mixed clinical expertise; and (3) with an anonymous web-based survey, investigate and compare attitudes toward preventable genomic medical errors among a national sample of genetics professionals and clinicians without specialist training in genetics. Our research will provide critical linkages between the fields of patient safety and genomic medicine, identifying new information about the range of potential errors associated with genomic testing, and about feasible systems-based approaches to mitigating those errors. These data will provide the foundation for the subsequent development and evaluation of interventions designed to identify and minimize errors associated with expanded clinical genomic testing.